I recently looked at spokes – Rose were definitely cheapest for DT Swiss as far as I could find.
Sapim were expensive everywhere.
CycleBasket do ACI which are marginally cheaper than the DT Swiss ones from Rose – although the ACI ones come with brass nipples where the DT Swiss don’t come with any.
I went with the DT Swiss ones in the end as I already had DT Rims and Squorx Nipples. They arrived fairly quickly (within a week). I’ve laced the wheels but not started tensioning yet so can’t comment on how they build up. Compared to the straight gauge Halo spokes I used on my last build they feel a bit flimsy / bendy. I don’t remember the ACI ones being quite the same – but they were a 26” build and this is a 650b so these might be a little longer.